This invention relates to mobile communications, and specifically to the provision of a clock in a mobile phone which may be set to a specific time zone setting.
Most mobile phones are equipped with a clock. In some digital cellular/PCS systems, such as the IS-95 CDMA system, the in-phone real-time clock is synchronized to the precise local time given by the base station to which the phone is communicating with currently. This feature is known as automatic local time adjustment. Users of such a real-time clock equipped phone do not need to adjust the real-time clock, even when they move to a different time zone.
Automatic local time adjustment, however, may be both confusing and detrimental to users in some instances. When a user and phone are near a time zone boundary, a base station co-located in the user""s time zone may drop service, and a base station in the next time zone may pick up service. This would, in conventional phones, change the local time shown on the phone. This may not be a serious problem, but may result in some confusion if the user relies on the phone clock for accurate time. A more serious problem arises if the phone has a personal organizer, or PDA, associated therewith, because events and schedules time-stamped in one time zone may be invalid when the phone is moved to another time zone, or when the time changes erroneously, e.g., the phone and user are near the eastern edge of a time zone and an appointment alert is set to alert the user 30 minutes from the present time. At present time plus one minute, a base station in the other time zone picks up the phone, and changes the time. As a result, the PDA will not alert the user to the appointment, as the PDA will xe2x80x9cbelievexe2x80x9d that the time for the appointment has passed. The known prior art which may be relevant to this invention includes:
Mobile Station-Base Station Compatibility Standard for Dual-Mode Spread Spectrum Systems, TIA/EIA-95-B.
U.S. Pat. No. 5,151,932, to Arizumi et al., for Method and system for selectively communicating with a telephone or a non-telephone terminal through a public telephone network, granted Sep. 29, 1992, describes a communications system which routes an incoming call depending on the time zone of the calling party.
U.S. Pat. No. 5,212,810, to Maeda et al., for Terminal equipment of a vehicle radio telephone system, granted May 18, 1993, describes a system wherein a terminal is automatically locked depending on the time zone to prevent unauthorized use of the equipment.
U.S. Pat. No. 5,258,964, granted Nov. 2, 1993, and U.S. Pat. No. 5,309,500, granted May 3, 1994, both to Koma et al., for Apparatus for displaying time-of-day data adaptively to different time zones, describe methods to determine the local time of day
U.S. Pat. No. 5,528,5 58, to Mardhekar et al., for International time indicating system, granted Jun. 18, 1996, describes a method of displaying the time zone of a called party to the caller.
U.S. Pat. No. 5,818,920, to Rignell et al., for Apparatus for controlling communication connections based on local time, granted Oct. 6, 1998, describes a method to notify a caller when a call is transferred to a different time zone.
U.S. Pat. No. 5,845,257, to Fu et al., for System and methods for scheduling and tracking events across multiple time zones, granted Dec. 1, 1998, describes a method of differentiating calls based on types of times, such as xe2x80x9clocal,xe2x80x9d xe2x80x9chomexe2x80x9d and xe2x80x9cremote,xe2x80x9d wherein a user manually specifies the current time zone in use.
U.S. Pat. No. 5,920,824, to Beatty et al., for Method for computing current time on a cellular mobile system, granted Jul. 6, 1999, describes a method to determine the current local time.
U.S. Pat. No. 6,075,992, to Moon et al., for Apparatus and method for automatically handling initiation of a call by a portable intelligent communications device, granted Jun. 13, 2000, describes a method of automatic call handling depending on the time zones of the calling party and the called party.
In a mobile phone having a clock display therein, wherein the mobile phone is in wireless communication with a base station located in a time zone having a current local time (CLT), and wherein the base station transmits a control signal having carried therein at least a universal coordinated time (UCT) signal, a system identification (SID) signal, a network identification (NID) signals, a CLT signal, and a daylight savings time (DST) flag, wherein the mobile phone is transportable to be in wireless communications with another base station in another time zone, and wherein, upon securing communications with a base station, the phone synchronizes its internal clock to the CLT of the base station; a clock includes a selection mechanism for use by a user to select a home time zone (HTZ), and to select a displayed time on the clock display from the group of displayed times consisting of CLT and HTZ; and a displayed time calculating mechanism which determines the time displayed on the clock display as a function of the CLT and the HTZ.
It is an object of the invention to provide a mobile communications device which will allow a user to maintain a selected time zone setting.
Another object of the invention is to provide a means to allow a user to select either a local time zone or a home time zone to be used in a mobile phone.
A further object of the invention is to provide, in a mobile phone, a mechanism for calculating a home time in a home time zone as a function of the local time given by a base station to which the mobile phone is connected.
Still another object of the invention is to provide a display of events, such as a personal schedule, a call log, etc., with times set by the user-selected time zone.
Another object of the invention is to provide, in a mobile phone, a mechanism for setting a home time zone automatically, as a function of the home system of the phone.
Another object of the invention is to provide a mechanism for notifying a user when more than one time zone may be associated with a home system.
A further object of the invention is to provide a mechanism allowing a user to select a single time zone as the xe2x80x9chome time zonexe2x80x9d from any possible time zones associated with the home system.
This summary and objectives of the invention are provided to enable quick comprehension of the nature of the invention. A more thorough understanding of the invention may be obtained by reference to the following detailed description of the preferred embodiment of the invention in connection with the drawings.